1. The Treaty of Versailles was too harsh on Germany. The treaty required Germany to give up territory, pay reparations, and accept responsibility for the war. This made it difficult for Germany to recover and led to widespread resentment.
2. The Great Depression. The Great Depression, which began in 1929, caused economic hardship all over the world. This made it even more difficult for Germany to pay its reparations, and led to further resentment.
3. The rise of Adolf Hitler. Hitler came to power in Germany in 1933. He quickly began to rearm Germany and to challenge the Treaty of Versailles. In 1939, Germany invaded Poland, which started World War II.
4. The failure of the League of Nations. The League of Nations was created after World War I to prevent future wars. However, it was unable to stop Germany from rearming or from starting World War II.
These are just some of the reasons why the treaties to end World War 1 were broken so quickly.